district court, for fact-finding purposes, may refer to the Commission, and the Commission may determine, questions of the amount and ownership of a claim by a United States national (as defined in section 6023 of this title), resulting from the confiscation of property by the Government of Cuba described in section 1643b(a) of this title, whether or not the United States national qualified as a national of the United States (as defined in section 1643a(1) of this title) at the time of the action by the Government of Cuba.